The long range goal for this research is to perform single particle tracking with quantum dots (qdots) to further our understanding of the role of SNARE proteins in neuronal membrane fusion. Presynaptic fusion is a key step in vesicle transport, and vesicle transport is involved in the delivery of vital neurotransmitters such as dopamine and other secretory hormones that are important in signaling and development. Further understanding of presynaptic fusion will enable better understanding of vesicle transport and thus the pathophysiology of neuropsychiatric conditions such as depression and addiction. In addition, understanding the functioning of SNAREs may even lead to the design of better drugs/therapy as one envisions enlisting SNAREs for fusion-enhanced targeted drug delivery Single particle tracking (SPT) of qdots will be performed to study the lateral diffusion of t-SNAREs on supported bilayer membranes with raft-forming lipids to address the inconsistent observations involving the phase preference for t-SNAREs in several recent studies. Proof-of-principle experiments will first be performed to optimize the experimental design and setup and to ascertain the efficacy of using qdots for single particle tracking. SPT of qdot-conjugated lipid will be used to study lipid diffusion in supported homogenous bilayers and heterogeneous bilayers with raft-forming lipids. t-SNARE diffusion in supported heterogenous bilayers will then be studied using SPT of qdot-conjugated SNAREs. Different mole fractions of t-SNAREs and different raft-forming lipid mixtures will be used, and cumulative distribution function will be used to fit the data to reveal multi-component diffusive behavior. [unreadable] [unreadable] [unreadable]